What age to start brooding?

I'm new to chickens got my first chicks in March and now I'm starting to get eggs. My rooster seems to be doing his "duty" and I was wondering at what age should I let a hen go broody?
I'm not sure if I can do it now or wait until they get a bit older. I would like to hatch a clutch this summer.

As a rule, the hen decides when and whether to go broody, not you. It is due to her hormones. Many will never go broody. Is is much more common in some breeds than others. However, one person says he has been successful making them go broody.